Coralline Algae

My question is regarding coralline algae...my tank has been running for over two years now. I guess I never gave it much thought, but I'd say recently within the last six months to a year all my coralline algae has disappeared. What would cause that? My tank is 55 gal w 20 gal fuge. I have attached a pic of about six months ago and a current pic for reference.

 

IMO
a few things could be happening.
have you changed your lighting?
test cal levels. Corals are growing and take more cal from the system.
Could also be low nutrients (like all algae needs)
Do you have urchins or asteria stars?

Tank looks great - like the growth

 

Lighting was recently changed, but the algae started to diminish before the change. My calcium has always been on the high side 490-500. Coral growth is great. I have an urchin and an over abundance of asteria stars.

Thanks for the compliment on the tank.

 

asteria stars would be the culprit IMO.

i am in the process of increasing my cal levels from 400-410 to 430. what do you do to get your cal that high? does it effect your pumps?

 

Urchins and Astraea will certainly eat coralline. What replaced it though? For example, green film algae or is it bare? I would suspect the former if bare, but if there is different agae, then perhapse phosphate went up a bit.

Of course changes in lighting do usually kill it, so, perhapse there was ac ombination of thing and that was the final nail in the coffin.

 

I don't dose anything. I do 5 gal water change once every week. I use kent marine salt.

I don't have any effect on my pumps.

 

I'm thinking a combination of lighting, urchin, and the starfish. Some green film algae has developed within the last couple months, but hasn't been a huge problem.

 

stupid question but have you checked your salinity? sometimes if that gets high the algae will die off faster than anything... i found this out one time when i left town and my buddy was topping off the tank with saltwater instead of fresh luckily it wasn't much and i noticed immediately when i got home the coraline on the back glass was almost all gone... no affect on fish or corals tho

 

Not a stupid question. My salt range has been between 1.024-026. I have been able to maintain that with an ATO.

 

i'm sure you have done this but if you haven't checked you might do that..

i remember reading on here that someone was getting higher salt some how while using an ATO.. the only reason i'm suggesting this is it might be so easy of a fix might not have thought about it